Electrical and Computer Engineering Commons^™

Distributed Fault Detection For A Class Of Large-Scale Nonlinear Uncertain Systems, Qi Zhang

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In the distributed large-scale system, the behavior of any subsystem is not only influenced by variables belonging to it (local variables), but also by the variables in other subsystems during its interaction with neighboring subsystems. The effect of the fault in one subsystem will be quickly propagated to other subsystems due to their interconnections. Currently, most of the fault detection and diagnosis schemes are focused on centralized system which do not consider the interaction terms and can not efficiently detect the faults.

In this thesis, a distributed fault detection scheme is developed for a class of large-scale nonlinear uncertain systems …

Self-Calibrating Cricket Motes For Indoor Navigation, Yogendra Jayant Patil

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Global Positioning System (GPS) plays a vital role for providing localization to the autonomous robots. But the quality of the GPS signal degrades in an indoor location and hence GPS cannot be used for indoor localization. Cricket motes are location-aware system that can provide localization service to its users in an indoor location. Cricket motes apply the acoustic ranging technique to find distance between two points. But before a user can use this localization system, assigning coordinate system to the motes requires manual assistance. This project presents a novel algorithm for self-calibration of the cricket motes to a coordinate system …

Graphene Based Rf/Microwave Impedance Sensing And Low Loss Conductor For Rf Applications, Iramnaaz Iramnaaz

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Biosensors are becoming more popular recently and expanding due to their broad applications in detecting disease and infectious agents, monitoring of environmental toxins, etc. Recognition and quantification of biochemical molecules and molecular interactions present great challenges in biosensing [38]. Impedance sensing at radio frequency (RF) /microwave frequency becomes very attractive as bio-molecules exhibits large distinct dielectric properties, and also because the ionic conductivity of water in most physiological systems is greatly diminished. For example, it has been reported that tumoral cells exhibits large value of electrical conductivity and permittivity which can result in significant variation of the impedance when compared …

Performance Analysis Of Radar Waveforms For Congested Spectrums, Shaun W. Frost

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With more users populating the RF spectrum and hence less available contiguous bandwidth, radar and communication waveforms are slowly forced to become more efficient at using their available frequencies. Two scenarios are considered: operation in a colored interference environment and operation in discontiguous spectral bands. Unconstrained algorithms for designing transmit waveforms and receive filters are evaluated, wherein varying a convex weight trades performance between spectral flatness and side lobe levels. An empirical study provides performance bounds for constrained radar waveform designs for an instantiation of the interference spectrum.

Closed-form predictions for integrated sidelobe ratio (ISLR) and peak-to-sidelobe ratio (PSLR) for …

Frequency Diverse Array Receiver Architectures, Aaron M. Jones

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Typical radar systems are limited to energy distribution characteristics that are range independent. However, operators are generally interested in obtaining information at particular ranges and discarding elsewhere. It seems appropriate then to attempt to put energy solely at the range(s) of interest, thus minimizing exposure to clutter, jammers and other range-dependent interferences sources. The frequency diverse array (FDA) can provide a mechanism to achieve range-dependent beamforming and the spatial energy distribution properties are investigated on transmit and receive for different architectures herein.

While simplified FDA receive architectures have been explored, they exclude the return signals from transmitters that are not …

Dynamic Footed With Clock Overlapping And Load Balancing In Multiple Paths For Noise Tolerance In Dynamic Cmos Circuits, Ramadan U. Buzakuk

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Dynamic CMOS circuits are used in microprocessors as well as in circuits that require high speed and small areas. Dynamic CMOS circuits have many advantages but are not robust in noise tolerance in comparison with the legacy static CMOS circuits. In this thesis several noise tolerance techniques that can be implemented with Dynamic CMOS circuits for robust noise tolerance are studied. A dynamic footed with clock overlapping technique integrated with a load balancing multiple-path transistor sizing algorithm for optimizing performance of noise tolerance and speed while in consideration of process variations is presented. Using the 2-bit weighted binary-to-thermometric converter implemented …

Commercial Program Development For A Ground Loop Geothermal System: Energy Loads, Gui, Turbulent Flow, Heat Pump Model And Grid Study, Paul A. Gross Ii

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The use of the earth's thermal energy to heat and cool building space is nothing new; however, the heat transfer approximations used in modeling geothermal systems, leave uncertainty and lead to over sizing. The present work is part of a Wright State effort to improve the computer modeling tools used to simulate ground loop geothermal heating and cooling systems. The modern computer processor has equipped us with the computation speed to use a finite volume technique to solve the unsteady heat equation with hourly time steps for multi-year analyses in multiple spatial dimensions. Thus we feel there is more need …

Commercial Program Development For A Ground Loop Geothermal System: G-Functions, Commercial Codes And 3d Grid, Boundary And Property Extension, Kyle L. Hughes

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The rise in fossil fuel consumption and green house gas emissions has driven the need for alternative energy and energy efficiency. At the same time, ground loop heat exchangers (GLHE) have proven capable of producing large reductions in energy use while meeting peak demands. However, the initial cost of GLHEs sometimes makes this alternative energy source unattractive to the costumer. GLHE installers use commercial programs to determine the length of pipe needed for the system, which is a large fraction of the initial cost. These commercial programs use approximate methods to determine the length of pipe mainly due to their …

Analysis And Comparison Of Popular Models For Current-Mode Control Of Switch Mode Power Supplies, Ramchandra M. Kotecha

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Current-mode control is the most popular scheme used for the operation of SMPS (Switch Mode Power Supplies). Current-mode control, also known as current-programmed mode or current-injected control is a multi-loop control scheme that has an inner loop and an outer voltage loop. The current loop controls the inductor peak current while the voltage loop controls the output voltage. The inner loop follows a set program by the outer loop. Some of the most popular small-signal models that predict the small-signal characteristics of current-mode control scheme have been analyzed and compared in this thesis. A PWM dc-dc buck converter in CCM(Continuous …

Analysis And Design Of Pulse-Width Modulated Two-Switch Forward Dc-Dc Converter For Universal Laptop Adapter, Venkata Sai Aditya Kumar Choragudi

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The objective of this research is to analyze, design and simulate a two-switch forward pulse-width modulated (PWM) DC-DC converter. The Forward PWM DC-DC converter is originally derived from the buck converter by the addition of a transformer. The transformer is mainly used as a safety feature to electrically isolate input and output stages of the power converter and also to scale the voltage or current. The steady-state analysis is presented for the two-switch PWM DC-DC forward converter in continuous conduction mode (CCM). Based on the analysis, the design equations for two-switch PWM forward DC-DC converter are derived. A design example …

Dc-Dc Power Converter Design For A Portable Affordable Welder System (Paws), Curt Stephen Zackiewicz

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Arc welding machines are typically large, heavy devices that transform an alternating current (AC) input into a low-voltage, direct current (DC) output. Traditionally these high power devices have required steel and copper transformers that account for their bulky size and weight. While the cost of raw materials in electromagnetic components has been increasing the cost of high-power silicon devices has been decreasing. This disparity creates an opportunity for a cost-effective DC-DC switching welder in the consumer market. While DC-DC power electronics are not new to the welding industry, this study, under the commission of a welding equipment manufacturer, aims to …

Observer-Based Fault Diagnosis Of Wind Turbines, Songling Zhao

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Because wind is a clean and renewable energy, it is in high demand as an alternative resource of fossil fuels for our daily power supply. Thus, wind turbine technology is wildly applied to convert the wind energy to electrical power. With the size of the wind turbines increased, the maintenance cost of the wind turbines also goes up. Fault diagnosis can significantly help wind turbines to: reduce the maintenance cost, the machinery breakdown, spare parts inventories, total machine downtime, and overtime expenses, and increase machine life, overall productivity, and profit. The technical challenges for fault diagnosis of the wind turbine …

Small-Signal Modeling Of Resonant Converters, Agasthya Ayachit

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Resonant DC-DC converters play an important role in applications that operate at high-frequencies (HF). Their advantages over those of pulse-width modulated (PWM) DC-DC converters have led to the invention of several topologies over the traditional forms of these converters. Series resonant converter is the subject of study in this thesis. By variation in the switching frequency of the transistor switches, the optimum operating points can be achieved. Hence, the steady-state frequency-domain analysis of the series resonant converter is performed. The operational and characteristic differences between the series resonant and parallel resonant and series-parallel resonant configurations are highlighted. In order to …

High-Frequency Wide-Range All Digital Phase Locked Loop In 90nm Cmos, Prashanth Muppala

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This thesis presents a high-frequency wide tuning range all digital phase locked loop (ADPLL) in 90 nm CMOS process with 1.2 V power supply. It operates in the frequency range of 2-7.2 GHz with wide linearity and high resolution. The ADPLL uses a wide frequency range digital controlled oscillator (DCO) and averaging technique to obtain fast lock time. The operation of the ADPLL includes both a frequency acquisition state and a phase acquisition state. A novel architecture is implemented in a coarse stage to obtain a monotonically increasing wide frequency range DCO for frequency acquisition and a fine control stage …

Ab Initio Simulations Of Graphene-Based Nanosensor For Detecting No2 And Li, Ahmed Jama Hassan

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Nanosensors, i.e., sensors based on nanomaterials, have the potential of superior performance owing to their size effect, and can have significant effects on detection of pollutants in the environment. Various nanowires have been used in this context. Here we investigate the possibility of NO2 and Li detection using the quantum conductance change in graphene nanoribbon. Quantum conductance modification in graphene nanoribbon upon NO2/Li adsorption was calculated using ab initio methods. The optimized structures of the adsorbed NO2 indicated two different geometries where either nitrogen or oxygen was closer to the graphene lattice. The former resulted in charge transfer from NO2 …

Capacitor Switching Transient Modeling And Analysis On An Electrical Utility Distribution System Using Simulink Software, Durga Bhavani Mupparty

University of Kentucky Master's Theses

The quality of electric power has been a constant topic of study, mainly because inherent problems to it can bring great economic losses in industrial processes. Among the factors that affect power quality, those related to transients originated from capacitor bank switching in the primary distribution systems must be highlighted. In this thesis, the characteristics of the transients resulting from the switching of utility capacitor banks are analyzed, as well as factors that influence there intensities. A practical application of synchronous closing to reduce capacitor bank switching transients is presented. A model that represents a real distribution system 12.47kV from …

Synthesis And Characterization Of P-Type Copper Indium Diselenide (Cis) Nanowires Embedded In Porous Alumina Templates, Sri Harsha Moturu

University of Kentucky Master's Theses

This work focuses on a simple template assisted approach for fabricating I-III-VI semiconductor nanowire arrays. Vertically aligned nanowires of p-CIS of controllable diameter and thickness are electrodeposited, from an acidic electrolyte solution, inside porous aluminum templates using a three electrode set up with saturated calomel electrode as the reference. AAO template over ITO-glass was used as starting template for the device fabrication. The deposited CIS is annealed at different temperatures in a reducing environment (95% Ar+ 5% H₂) for 30 minutes. X-ray diffraction of the nanowires showed nanocrystalline cubic phase structures with a strong orientation in the <112> direction. …

Gaze Estimation Using Sclera And Iris Extraction, Prashanth Rao Periketi

University of Kentucky Master's Theses

Tracking gaze of an individual provides important information in understanding the behavior of that person. Gaze tracking has been widely used in a variety of applications from tracking consumers gaze fixation on advertisements, controlling human-computer devices, to understanding behaviors of patients with various types of visual and/or neurological disorders such as autism. Gaze pattern can be identified using different methods but most of them require the use of specialized equipments which can be prohibitively expensive for some applications. In this dissertation, we investigate the possibility of using sclera and iris regions captured in a webcam sequence to estimate gaze pattern. …

Design And Analysis Of Macro Switched Impedance Motors, Weston C. Johnson

Theses and Dissertations--Electrical and Computer Engineering

For present day global economies energy use is the single most important criteria determining a nation’s wealth and sustainability. The global energy needs are met primarily by fossil fuels which are of finite supply. One means to extend the life span of the fossil fuel reserves has been to improve the efficiency of existing systems including generation, storage, usage etc., as a means of conservation. This dissertation investigates a motor technology that promises to complement existing conservation techniques.

Given advances in high voltage power semiconductors, manufacturing techniques and materials research this dissertation evaluates the potential of the switched impedance motor …

Channel Coding Over Multiple Coherence Blocks With Queueing Constraints, Deli Qiao, M. Cenk Gursoy, Senem Velipasalar

Department of Electrical and Computer Engineering: Faculty Publications

This paper investigates the performance of wireless systems that employ finite-blocklength channel codes for transmission and operate under queueing constraints in the form of limitations on buffer overflow probabilities. A block fading model, in which fading stays constant in each coherence block and change independently between blocks, is considered. It is assumed that channel coding is performed over multiple coherence blocks. An approximate lower bound on the transmission rate is obtained from Feintein’s Lemma. This lower bound is considered as the service rate and is incorporated into the effective capacity formulation, which characterizes the maximum constant arrival rate that can …